The present invention relates to spools and bobbins for sewing thread and other filamentous material and adapted for use in home and commercial sewing machines, and more particularly to a spool adapted to releasably hold one or two bobbins. In the past, sewing machine operators spent a substantial amount of time winding the desired thread onto a bobbin or hunting for one that had previously been wound, before inserting the loaded bobbin into its socket provided below the sewing machine platen and needle. Typically, the desired bobbin was buried in a sewing box and or entangled with loose threads dangling from other bobbins.
The closest prior art known to the inventor is U.S. Pat. No. Des. 250,338 issued Nov. 21, 1978 to LaPierre. LaPierre discloses a combined spool and bobbin holder wherein one end of the spool is equipped with four relatively spaced apart prongs projecting upwardly therefrom. The prongs appear to be shaped and positioned so that a bobbin can be wedged between them and held in place on top of the spool.
Certain problems are inherent in the LaPierre design. The prongs increase the length of the spool, making it difficult or impossible to use where a limited amount of space is provided. During rotation of the spool, the prongs could catch on anything they touch. The positions of the prongs on the LaPierre spool depends upon the diameter of the spool. On a relatively small spool, the prongs will be relatively close to the outer edge. On a larger spool, they will be set inwardly from the outer edge so that the distance between the prongs remains constant. Since the prongs appear to be shorter than a conventional bobbin, the thread could unwind from a bobbin seated upon the LaPierre spool. Further, since the LaPierre spool is less compact than conventional spools, packaging and storage problems may arise.
Thus, the present inventor was faced with the problems of keeping spools and bobbins containing the same thread together, preventing the bobbin thread from unwinding in storage, and designing bobbin-receiving features that would remain constant and not alter the conventional spool sizes.